1) Field of the Invention
The invention herein relates to an improved structure safety syringe that is simple, easy to operate, and offers a high degree of utilization safety.
2) Description of the Prior Art
Since AIDS, hepatitis type A, and hepatitis type B are transmitted by the re-use of hypodermic needles, the use of disposable needles is the basic safeguard in preventing the spread of such communicable diseases.
While the use of disposable hypodermic needles ensures the safety of the persons receiving injections, medical treatment personnel face substantial risks, especially after administering injections to patients. When a hypodermic needle is placed back into its cover, a self-inflicted puncture can easily occur due to accidental impact or carelessness. To minimize such hazardous situations, a safer type of syringe has now been successfully developed (new patent application No. 86,214,720). As indicated in FIG. 1, the said syringe is comprised of a barrel 1, a sleeve 2, and a plunger 3; the said barrel 1 is of a hollow cylindrical construction and has a hypodermic needle 4 installed at one end and a one-way plunger opening 101 at the other end; a short round tab 102 is disposed on the circumferential surfaces at the two sides of the barrel 1 near the hypodermic needle 4; two guide slots 201 are formed lengthwise along the walled surface of the said sleeve 2, a limit slot 202 extends from the circumferential surface at the two ends of the said guide slots 201 and, furthermore, the limit slots 202 and the guide slots 201 merge perpendicularly, and a sleeve opening 203 is formed inside the sleeve 2 and, furthermore, a notch 204 that extends up to the limit slot 202 is formed along the annular surface of the sleeve opening 203 of the sleeve 2; as such, when the barrel 1 is inserted into the sleeve opening 203 of the sleeve 2, the tab 102 situated along the notch 204 is inserted into the guide slot 201; furthermore, after the injection is administered, the operator pulls the sleeve 2 over the barrel 1 and, furthermore, with the tab 102 now positioned at one end of the guide slot 201, rotates it an appropriate number of degrees, causing the tab 102 to move into the limit slot 202, thereby preventing the separation of the sleeve 2 and the barrel 1 and, furthermore, causes the hypodermic needle 4 to be housed within the sleeve 2 to achieve the objective of safety.
However, when the tab 102 is moved into the limit slot 202, the limit slot 202 does not provide any effective positional latching such that the sleeve 2 is easily rotated over the barrel 1 in the opposite direction for an appropriate number of degrees and, therefore, the sleeve 2 may slip back and, furthermore; cause the hazardous exposure of the hypodermic needle 4.
Additionally, since the sleeve 2 is constructed of a plastic material, it readily deforms when subjected to squeezing, at which time the hypodermic needle 4 may protrude out of the guide slot 201, resulting in the hazardous infliction of a puncture wound.
In view of the said situation, the inventor of the invention herein devoted extensive thought to the matter and, furthermore, conducted many years of research, development, and testing which culminated in the successful completion of the present invention.